Field of the Invention
The invention relates to a touch-link electronic device, a near-field wireless communications system and a near-field wireless communications method, and more particularly to an electronic device, a near-field wireless communications system and a near-field wireless communications method that are capable of improving the security of a communications link.
Description of the Related Art
NFC (Near Field Communication) is a contactless identification and interconnection technology, which allows users to intuitively exchange information and access content and services among mobile devices, consumer electronics, personal computers, or intelligent electronic devices using methods of near magnetic field communication, such as using 13.56 MHz of near magnetic field communication.
Since the market demand for integrated NFC in handheld devices such as mobile phones is mature, NFC now supports mobile payment or can act as a point-of-sale (POS) system. However, since NFC is established based on magnetic fields to transmit and receive signals, it is necessary to install inductive card readers or some components with a similar function in handheld devices or mobile phones to support NFC, which causes the handheld devices to become larger and poses a limitation to the layout structure and component material of the mobile phones and other handheld devices.
Along with the development of touch-sense technology, touch-control panel devices have become more and more popular. In one application of touch-sense technology, a touch-control panel device can detect and respond to the contacts of a user. Besides the touch-sense technology, there is the recently developed “touch-link technology” for touch-control panel device, such as that recited in patent applications US 2011/0304583, US 2013/0147760, and CN 102916729A, which implements near-field wireless communications by utilizing the existing touch-control panel and the corresponding hardware devices. Generally, a touch-control panel device includes a touch panel, a signal processing circuit and a central processing unit (CPU). For example, the touch-control panel device may contain a touch pad without display function or a touch screen with display function. The touch-control panel device may include a touch sensor. The touch sensor includes a plurality of driving electrodes and a plurality of sensing electrodes on a substrate. The touch-control panel device is usually implemented by a coating of Indium Tin Oxide (ITO) materials. The signal processing circuit is usually implemented by integrated circuit (IC). The signal processing circuit performs two main functions. One is performing analog-to-digital (ADC) conversion, demodulation, or other signal processing tasks on the analog signals received from the touch panel, and then transmitting the processed signals to the CPU. The other is receiving digital signals from the CPU, performing modulation, digital-to-analog (DAC) conversion, or other signal processing tasks on the received digital signals and then transmitting the processed signals to the touch panel. In an application of touch-sense technology, when a user touches the touch-control panel device with his finger or a stylus, corresponding analog signals are generated by the driving electrodes and sensing electrodes via the touch sensor. The signals are transmitted to the CPU after being processed by the signal processing circuit. The CPU calculates the touch position via proper algorithm(s) and responds to the contacts of the user. In the application of touch-link technology, the driving electrode and/or the sensing electrode can act as a transmitting electrode for transmitting signals, and the driving electrode and/or the sensing electrode can act as a receiving electrode for receiving signals. When transmitting signals, a touch-control panel device can modulate and process the signal to be transmitted by the signal processing circuit, and transmit the processed signals to another touch-control panel device via the transmitting electrode by electric field coupling. The receiving electrode of the another touch-control panel device receives the transmitted signal. When receiving signals, a touch-control panel device can receive a signal via the receiving electrode by electric field coupling, demodulate the signals by the signal processing circuit, and then transmit the processed signal to the CPU for further processing. Therefore, the signals can be transmitted and received by using the original electrodes to realize touch transmission based on electric fields without an inductive card reader or components with a similar function being incorporated. Compared to conventional NFC technology, touch-link technology reduces both volume and cost. Of course, touch-link technology also works when not using the existing hardware such as the existing touch-control panel device, but using another touch-control panel and the signal processing circuit to realize touch-link technology. In addition, in the application of touch-sense technology, there are two common types of touch-control panel devices, capacitive touch and resistive touch. For the applications of touch-link technology, besides the capacitive type of touch-control panel device, the resistive type of touch-control panel device can also be used to realize the touch-link technology.
On the other hand, establishing a communications link, such as the WiFi-Direct or Bluetooth, between two electronic devices have also become more and more popular. For one electronic device, the most common way to establish a communications link is to first search another nearby device, then exchange information regarding the communications link, and finally perform a pairing to establish the communications link. However, in an environment dense with electronic devices, it is inevitable that some irrelevant devices will be found during the search procedure, causing trouble and security problems when establishing the communications link. One of the limitations of using NFC technology completing a WiFi-Direct or Bluetooth pairing is the short distance required, such as 20 cm, yet the 20 cm range is still too far for some scenarios. When the user does not turn off the NFC pairing functionality, intruders can come close to the electronic device and invade the electronic device to steal data with the user unaware.
Therefore, in order to improve the security of such communications link, improved electronic devices and communications methods are proposed. Two electronic devices can not only exchange information for establishing the communications link without using the NFC technology, but also greatly improve the communications security by adjusting the effective distance of the communications.